The present invention relates to a process and a device for opening folded printed products, in particular newspapers, magazines and parts thereof.
It is known, for example from U.S. Pat. No. 4,489,930 and the corresponding EP-A-0 095 603, to hold eccentrically folded printed products, where the fold runs transversely to the direction of conveyance, with transporting clamps and to transport them suspended obliquely towards the rear. In this type of arrangement, an opening device is disposed beneath the conveying device. The opening device has a continuous belt which is driven at the transport velocity of the conveying device, on which belt there are disposed grippers, at a distance from the transporting clamps. The active strand of the belt runs parallel to the direction of conveyance and a supporting mechanism is connected upstream from the belt in order to support the printed products in their trailing end area lying opposite the fold. Adjoining the belt (viewed in the direction of conveyance) is a small conveyor belt, which revolves at a higher speed in relation to the transport velocity of the conveying device. The uppermost product part has a marginal section, in the end area, which protrudes over the shorter, bottommost product part. This marginal section is grasped, in each case, by a gripper of the opening device and clamped in place between the gripper itself and the belt. The bottommost, shorter product part is moved, bulging out as it does so, by the faster-running, small conveyor belt away from the held product part in the direction of conveyance and the print product thereby opened. A collecting bar of a collecting device runs into the opened print product, in each case, between the product parts which have been lifted apart. Following the release of the printed products by the transporting clamps, the printed products fall astride onto the collecting bars.
Using this known process and using this known device, only printed products which are transported with a trailing end area and an uppermost marginal section can be transported. Reliable opening of the printed products is only possible if the paper has a low natural stiffness, the bottommost product part has a certain weight and further the leaves do not stick together.
U.S. Pat. No. 4,684,117 and the corresponding EP-A-O 208 081 further disclose a process and a device for opening eccentrically folded printed products having a trailing fold (viewed in the direction of conveyance) and a leading marginal area lying opposite the fold. The printed products are held, at the fold, by individually controllable grippers of a conveying device and transported in a direction of conveyance running obliquely from top to bottom. In this arrangement, an opening device is provided beneath the conveying device. The opening device includes grippers disposed on a revolutionally or revolvingly driven drawing member. Laterally, next to the drawing member, there is provided a fixed supporting plate and, connected upstream from this, a revolutionally or revolvingly driven, continuous supporting belt to support the printed products in the leading end area. If the printed products are transported such that the product part having the marginal section protruding over the shorter product part is bottommost, the corresponding gripper is transferred into the open position and the particular transporting 3 clamp of the conveying device is opened for a short time so that the marginal section slides into the mouth of the gripper. The bottommost product part held by the marginal section is now, when the drawing member is deflected around a deflection pulley, moved away from the other, non-held product part in a direction transverse to the direction of conveyance. Between the product parts which are thus partially lifted apart, there is introduced a collecting conveyor on which the printed product falls astride whenever the transporting clamp is opened.
If, on the other hand, the printed products are transported with the product part having the marginal section uppermost, then when the respective gripper is opened, the marginal section gripped underneath by a clamping tongue of the gripper is raised up and the respective transporting clamp is opened for a short time. In this manner, the bottommost shorter product part slides into the working area of the gripper. After the gripper is closed, the shorter product part held thereby is in turn deflected, upon the deflection of the gripper, around the deflection pulley in a direction transverse to the direction of conveyance. In order to open the printed product, the shorter product part is moved away from the non-held, uppermost product part. This known process and the corresponding device, only contemplate the opening of printed products which are transported with a trailing fold and a leading end area and a direction of conveyance running obliquely from top to bottom. Furthermore, reliable opening of the printed products is not assured if the products have a very low natural stiffness and stick together.
It is therefore an object of the present invention to refine the process of the generic type and provide a corresponding device, wherein opening of printed products is reliably guaranteed.
It is a further object of the present invention to provide a process for opening printed products and a corresponding device wherein opening is independent from the position and nature of the printed products.